نتایج جستجو برای: go optical band gap

تعداد نتایج: 586818  

2014
John J. Carey Jeremy P. Allen David O. Scanlon Graeme W. Watson

In this study, density functional theory is used to evaluate the electronic structure of the antimony chalcogenide series. Analysis of the electronic density of states and charge density shows that asymmetric density, or ‘lone pairs’, form on the Sb cations in the distorted oxide, sulphide and selenide materials. The asymmetric density progressively weakens down the series, due to the increase ...

2011
D. A. Bonnell

The measured optical and transport properties of singlecrystal SrTiO3 have been determined as a function of oxidation and reduction using spectroscopic ellipsometry, Hall and resistivity measurements. A decrease in the valence to conduction band transitions across the band gap, from O 2p to Ti 3d states, is observed by decreases in both the index of refraction and the extinction coefficient at ...

پایان نامه :دانشگاه تربیت معلم - تبریز - دانشکده علوم 1389

فیلتری باساختارپریودیک سه گانه یک بعدی مطرح شده وروابط پراکندگی در ان بررسی میشود.با انالیز ریاضی می توان باندهای ممنوعه و مجاز طول موجها را با تغییرات زاویه فرودی پیش بینی کرد.با استفاده از روابط پراکندگی و با انتخاب مقادیر مناسب پارامترهای کنترلی میتوان طرح یک فیلتر اپتیکی را داد که می تواند در همه رنجهای طیف الکترومغناطیسی بکار گرفته شود.این مطالعه میتواند برای بهبود کارایی و دقت pbg(photoni...

2015
A. F. Mansour S. F. Mansour M. A. Abdo

The structural and optical properties of polyvinyl alcohol (PVA) doped with different concentrations (0, 0.15, 0.5, 1, 2, 2.5, and 3 wt %) of ZnO nanoparticles were studied. ZnO nanoparticles were prepared by the solgel methode, and nanocomposite films were prepared using the solution casting methode. Nanocomposites films were characterized by X-ray diffraction (XRD), Fourier Transformer Infrar...

Journal: :Physical review letters 2007
Sajeev John Shengjun Yang

It is suggested that an exciton in the engineered vacuum of a photonic-band-gap-quantum-well heterostructure exhibits electromagnetically induced anomalous quantum dynamics. The exciton is dressed by coherent emission and reabsorption of virtual photons near the photonic band edge and captured in momentum space, lowering its energy by 1-10 meV and lowering its effective mass by 4-5 orders of ma...

Journal: :Catalysts 2023

The synthesis of CaCO3/Cu2O/GO nanocomposites was developed by sol-gel auto-combustion method. analysis structure completed on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and environmental scanning electron microscopy (ESEM). XRD spectra the matched crystal CaCO3/Cu2O. average size 20 nm for Cu2O 25 CaCO3 nanoparticles. FTIR data showed absorptio...

Journal: :international journal of nanoscience and nanotechnology 2012
n. qutub s. sabir

the present work deals with the synthesis and characterization of cds nanoparticles with good thermal stability and optical properties by a novel and simple synthetic route. the nanoparticles were synthesized via chemical precipitation method in a single reaction vessel under ambient conditions. the prepared cds nanoparticles were compared with the bulk cds. the optical properties were determin...

Journal: :iranian journal of science and technology (sciences) 2013
m. ramya

copper sulphide (cu 2 s) thin films at different thicknesses and annealing temperatures were deposited onto glass substrate by vacuum evaporation method. xrd study reveals the phase transformation of cu     2 s film at higher thickness. optical and resistivity study show the phase transformation of the film from cu     2 s to cus when they are annealed at higher temperature. sem st...

Journal: :Physical review letters 2014
Søren Ulstrup Jens Christian Johannsen Federico Cilento Jill A Miwa Alberto Crepaldi Michele Zacchigna Cephise Cacho Richard Chapman Emma Springate Samir Mammadov Felix Fromm Christian Raidel Thomas Seyller Fulvio Parmigiani Marco Grioni Phil D C King Philip Hofmann

Bilayer graphene is a highly promising material for electronic and optoelectronic applications since it is supporting massive Dirac fermions with a tunable band gap. However, no consistent picture of the gap's effect on the optical and transport behavior has emerged so far, and it has been proposed that the insulating nature of the gap could be compromised by unavoidable structural defects, by ...

2012
Muge Acik Yves J. Chabal

Exfoliation, i.e. individual separation of carbon sheets, is of great interest to produce single-layered graphene nanosheets. Chemical or thermal treatments are popular approaches to exfoliate graphite chunks. In general, these conventional methods are assisted with intercalation via covalent or non-covalent functionalization, expansion, and swelling, adsorption of organic molecules in gas phas...

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